Dogs Sniff Out Environmental Injustice

Dogs Sniff Out Environmental Injustice

Photograph by Matthieu Croizier / Connected Archives


The nosy canines track mink and otter scat on Blackfeet Land, which scientists test for food, water, and ecosystem contamination.

Souta Calling Last starts each day gathering fresh mint for her tea, cutting bark from willow trees, and collecting sagebrush and stones to use in a sweat lodge. She splashes water from the local river onto the hot stones, quiets her mind, and gives thanks.


“It’s a ritual that many of us practice,” said Calling Last, a member of the Blackfeet and Blood Nations, which are part of the Blackfoot Confederacy. This Indigenous tradition heals the body and calms the mind. “The water evaporates and we breathe in the smells from the herbs and drink the tea.”


Calling Last is the founder and executive director of Indigenous Vision, a nonprofit that provides educational resources to revitalize Indigenous land and communities. Her home, Blackfeet Reservation in Montana, spans 1.5 million acres and includes some 10,000 people. It faces pollution from oil and gas drilling and illegal dumping of commercial and industrial waste, both of which leak contaminants into local food and water. On her quest to map tainted sites, Calling Last has turned to an unlikely sidekick: working dogs. These specially trained canines can sniff out what humans can’t. Right now, they’re searching for mink and otter droppings, which scientists later test for heavy metals. But that’s just the beginning. The dogs are also learning to detect PFAS, prions, and other concerns as they arise. 


In 2022, Calling Last approached Working Dogs for Conservation (WD4C), a nonprofit that trains detection dogs for wildlife conservation projects. Together, they launched the Blackfeet Environmental Justice Program. Most of WD4C’s recruits come as rescues from local animal shelters. On their days off, they live like most well-loved canines—lapping up praise and relishing life with their handlers. Calling Fast herself has a working dog in training: Itoomaa, a cocker spaniel puppy living with her at Blackfoot Reservation. 


“We train our dogs for a variety of tasks depending on whom we work with and where we work,” said Michele Lovara, a canine field specialist at WD4C. “They can detect invasive plants in the seedling stage, animals that live underground, and endangered animals.” For this project, the dogs were trained to hunt for mink and otter scat, which are later analyzed for heavy metals like arsenic, copper, mercury, and lead


With the dogs’ help, Calling Last is mapping where the contaminated scat is found. Once complete, she will post that alongside Indigenous Vision’s other publicly available maps, which include those of tribal businesses, hate crimes against Indigenous people, and more. The resource will pinpoint hotspots for cleanup and warning zones for food, water, and ritual gatherings. “Long-term exposure to these chemicals harms aquatic ecosystems, local wildlife, and people living in these communities,” Calling Last said. “The dogs have been tremendously helpful in finding what we cannot see.” 


During sampling trips, Lovara gets up at sunrise. Like any good dog owner, she makes sure it isn’t too hot or too cold before heading out. Then, the adventure begins. She drives two to three hours with another member of WD4C and two detection dogs: Frost, a three-year-old English springer spaniel/pit bull mix, and Sully, a six-year-old border collie/golden retriever mix.

Their sensitive noses, along with their trainability, make dogs formidable partners for sniffing out scents that are unperceivable to us.

Frost roams through open fields, Lovara hot on his tail. They trace the edges of a nearby lake, periodically taking in the commanding view of Glacier National Park in the distance. Careful not to overwork the animals, the pair return to the vehicle after a mile, passing the baton to Sully and his handler. “It’s hard to spot the scat on our own. The dogs work faster, cover more territory, and find what we don’t see,” Lovara said.


That’s due to their tremendous sense of smell. 


Researchers estimate that dogs have between 125 million to 800 million olfactory receptors in their nose, said Dr. Nicholas Dodman, professor emeritus at Cummings School of Veterinary Medicine at Tufts University and cofounder of the Center for Canine Behavior Studies. “Bloodhounds have up to four billion olfactory receptors,” he said. Humans, on the other hand, have a mere five to 12 million. 


Their sensitive noses, along with their trainability, make dogs formidable partners for sniffing out scents that are unperceivable to us. Dodman, for example, recalled an experiment where a dog located a small piece of pork sealed in a box and dropped in a lake. “The dog was placed on a small boat, and each time he circled the spot where the pork was, he barked,” Dodman said. “Dogs have been trained to detect cancer and they can pick up the scent from a person’s breath.” He’s not surprised they can find mink and otter scat in such an expansive area. 


The Blackfeet Environmental Justice Program’s dogs are learning to detect emerging contaminants as new concerns arise. A few weeks ago, for example, Calling Last received notice that a recently closed auto supply shop in the area dumped antifreeze and oil in a nearby river. She’s worried about PFAS, which are chemicals used to enhance resistance to heat, oil, and water. These “forever chemicals” stubbornly persist in ecosystems, wildlife, and our bodies, and they have been linked to cancer, reproductive problems, endocrine disruption, and a suite of other health effects. Calling Fast has since sent water and soil samples to the lab for analysis, and the program is currently training dogs to locate PFAS in animal scat.


Similarly, the dogs are learning to detect chronic wasting disease (CWD), a fatal neurological illness that affects elk, deer, moose, and caribou. CWD is caused by prions—transmissible proteins that make other proteins in the brain fold incorrectly. The disease causes weight loss, listlessness, excessive salivation, and eventually, death. A local hunter recently brought Calling Last a deer head that tested positive, and several other suspected cases are undergoing analysis with the lab.


Although CWD doesn’t currently infect humans, it means near-certain death for other species. And what harms the food web harms us all. We’re interconnected—a fact that Calling Last’s tea ceremony reminds her of each day. Our species deals unrivaled injury to those around us. Still, we can only mitigate the problems that we can detect—a limit set by our narrow sensory capacity. Calling for help from nonhuman animals like dogs might seem unorthodox, but we owe it to them: Only by transcending the human ego can we protect the planet for us all.

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